From: Masatake YAMATO <yamato@redhat.com>
Date: Thu, 31 Aug 2023 18:20:20 +0000 (+0900)
Subject: tests: (lsfd) avoid race conditions (part 1)
X-Git-Tag: v2.40-rc1~253^2~4
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0fec4965f6c0f95b56df8ae67a77a1bdc4dda8a1;p=thirdparty%2Futil-linux.git

tests: (lsfd) avoid race conditions (part 1)

For terminating test_mkfds process, the test cases
used SIGCONT. test_mkfds used pselect for waiting for the signal.
After receiving the signal test_mkfds exited.

There is a race condition in this logic. If a test case sends SIGCONT
to test_mkfds process before the process calls pselect, the signal
may be lost. As the result, test_mkfds keeps waiting forever in pselect.

This change replaces the code sending SIGCONT with writing to the pipe
connecting to the stdin of test_mkfds. test_mkfds also monitors
its stdin in the pselect call. Unlike the signal, the written bytes to
the pipe are queued.

This change doesn't touch tests/ts/lsfd/option-inet and option-summary
test cases. They don't use coproc. So fixing the race condition in the test
cases can be much complicated. I will make a dedicated pull request (part 2)
for them.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
---

diff --git a/tests/ts/lsfd/column-ainodeclass b/tests/ts/lsfd/column-ainodeclass
index 6391c48165..3a10026c21 100755
--- a/tests/ts/lsfd/column-ainodeclass
+++ b/tests/ts/lsfd/column-ainodeclass
@@ -38,7 +38,7 @@ for C in pidfd inotify; do
 	    ${TS_CMD_LSFD} -n -o ASSOC,STTYPE,AINODECLASS -p "${PID}" -Q "${EXPR}"
 	    echo "$C"':ASSOC,STTYPE,AINODECLASS': $?
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
     } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/column-deleted b/tests/ts/lsfd/column-deleted
index 7898029d46..128cd0e8a5 100755
--- a/tests/ts/lsfd/column-deleted
+++ b/tests/ts/lsfd/column-deleted
@@ -38,7 +38,7 @@ ts_init_subtest $C
 	EXPR='(FD == '"$FD"')'
 	${TS_CMD_LSFD} -p "$PID" -n -o DELETED -Q "${EXPR}"
 	echo "$C: DELETED: " $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } >  "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
@@ -52,7 +52,7 @@ ts_init_subtest $C
 	EXPR='(FD == '"$FD"')'
 	${TS_CMD_LSFD} -p "$PID" -n -o DELETED -Q "${EXPR}"
 	echo "$C: DELETED: " $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } >  "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
diff --git a/tests/ts/lsfd/column-name b/tests/ts/lsfd/column-name
index 0cac74bdea..a9d46879ad 100755
--- a/tests/ts/lsfd/column-name
+++ b/tests/ts/lsfd/column-name
@@ -60,7 +60,7 @@ for C in ro-regular-file pidfd socketpair; do
 	    }
 	    echo "$C"':ASSOC,KNAME,NAME': ${PIPESTATUS[0]}
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
     } > "$TS_OUTPUT" 2>&1
     wait "${MKFDS_PID}"
@@ -81,7 +81,7 @@ ts_init_subtest deleted-file
 	    sed -e 's#.*/\([^/]\+\)#\1#'
 	echo "$C: DELETED,NAME: " ${PIPESTATUS[0]}
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } > "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
diff --git a/tests/ts/lsfd/column-source-with-root b/tests/ts/lsfd/column-source-with-root
index 70a9714caa..c00ee155c6 100755
--- a/tests/ts/lsfd/column-source-with-root
+++ b/tests/ts/lsfd/column-source-with-root
@@ -35,7 +35,7 @@ ts_init_subtest SysVIPC-shmem
     if read -u ${MKFDS[0]} PID; then
 	${TS_CMD_LSFD} -p "$PID" -n -o ASSOC,SOURCE -Q "${EXPR}"
 	echo 'ASSOC,SOURCE': $?
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/column-type b/tests/ts/lsfd/column-type
index cf6175efaa..8ededd44f3 100755
--- a/tests/ts/lsfd/column-type
+++ b/tests/ts/lsfd/column-type
@@ -46,7 +46,7 @@ for C in ro-regular-file pidfd inotify socketpair; do
 	    ${TS_CMD_LSFD} -n -o ASSOC,STTYPE,TYPE -p "${PID}" -Q "${EXPR}"
 	    echo "$C"':ASSOC,STTYPE,TYPE': $?
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
     } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/column-xmode b/tests/ts/lsfd/column-xmode
index 651f53277a..4de623ff00 100755
--- a/tests/ts/lsfd/column-xmode
+++ b/tests/ts/lsfd/column-xmode
@@ -39,7 +39,7 @@ ts_init_subtest "MODE-r-bit"
     if read -r -u "${MKFDS[0]}" PID; then
 	"${TS_CMD_LSFD}" -n -o MODE -p "${PID}" -Q "${EXPR}"
 	echo "MODE(r-bit): " $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } > "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
@@ -51,7 +51,7 @@ ts_init_subtest "XMODE-r-bit"
     if read -r -u "${MKFDS[0]}" PID; then
 	"${TS_CMD_LSFD}" -n -o XMODE -p "${PID}" -Q "${EXPR}"
 	echo "XMODE(r-bit): " $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } > "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
@@ -64,7 +64,7 @@ ts_init_subtest "MODE-w-bit"
     if read -r -u "${MKFDS[0]}" PID; then
 	"${TS_CMD_LSFD}" -n -o MODE -p "${PID}" -Q "${EXPR}"
 	echo "MODE(w-bit): " $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } > "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
@@ -76,7 +76,7 @@ ts_init_subtest "XMODE-w-bit"
     if read -r -u "${MKFDS[0]}" PID; then
 	"${TS_CMD_LSFD}" -n -o XMODE -p "${PID}" -Q "${EXPR}"
 	echo "XMODE(w-bit): " $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } > "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
@@ -92,7 +92,7 @@ else
 	if read -r -u "${MKFDS[0]}" PID; then
 	    "${TS_CMD_LSFD}" -n -o MODE -p "${PID}" -Q "${EXPR}"
 	    echo "MODE(x-bit): " $?
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
     } > "$TS_OUTPUT" 2>&1
     wait "${MKFDS_PID}"
@@ -108,7 +108,7 @@ else
 	if read -r -u "${MKFDS[0]}" PID; then
 	    "${TS_CMD_LSFD}" -n -o XMODE -p "${PID}" -Q "${EXPR}"
 	    echo "XMODE(x-bit): " $?
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
     } > "$TS_OUTPUT" 2>&1
     wait "${MKFDS_PID}"
@@ -122,7 +122,7 @@ ts_init_subtest "XMODE-D-bit"
     if read -r -u "${MKFDS[0]}" PID; then
 	"${TS_CMD_LSFD}" -n -o XMODE -p "${PID}" -Q "${EXPR}"
 	echo "XMODE(D-bit): " $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } > "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
@@ -135,7 +135,7 @@ for m in flock-sh posix-r- ofd-r-; do
 	if read -r -u "${MKFDS[0]}" PID; then
 	    "${TS_CMD_LSFD}" -n -o XMODE -p "${PID}" -Q "${EXPR}"
 	    echo "XMODE(l-bit): " $?
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
     } > "$TS_OUTPUT" 2>&1
     wait "${MKFDS_PID}"
@@ -150,7 +150,7 @@ touch "$f"
     if read -r -u "${MKFDS[0]}" PID; then
 	"${TS_CMD_LSFD}" -n -o XMODE -p "${PID}" -Q "${EXPR}"
 	echo "XMODE(l-bit): " $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } > "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
@@ -164,7 +164,7 @@ for m in flock-ex posix--w posix-rw  ofd--w ofd-rw lease-w; do
 	if read -r -u "${MKFDS[0]}" PID; then
 	    "${TS_CMD_LSFD}" -n -o XMODE -p "${PID}" -Q "${EXPR}"
 	    echo "XMODE(L-bit): " $?
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
     } > "$TS_OUTPUT" 2>&1
     wait "${MKFDS_PID}"
@@ -180,7 +180,7 @@ ts_init_subtest "XMODE-m-bit"
     if read -r -u "${MKFDS[0]}" PID; then
 	"${TS_CMD_LSFD}" -n -o XMODE -p "${PID}" -Q "${EXPR}"
 	echo "XMODE(m-bit): " $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 } > "$TS_OUTPUT" 2>&1
 wait "${MKFDS_PID}"
diff --git a/tests/ts/lsfd/filter-floating-point-nums b/tests/ts/lsfd/filter-floating-point-nums
index 1dfcfc78e5..05bf5d551d 100755
--- a/tests/ts/lsfd/filter-floating-point-nums
+++ b/tests/ts/lsfd/filter-floating-point-nums
@@ -78,7 +78,7 @@ EXPR=
 	${TS_CMD_LSFD} -n -o FD,TIMERFD.INTERVAL -p "$PID" -Q "$EXPR"
 	echo "FD,TIMERFD.INTERVAL: $EXPR": $?
 	
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     
     wait "${MKFDS_PID}"
diff --git a/tests/ts/lsfd/mkfds-bpf-prog b/tests/ts/lsfd/mkfds-bpf-prog
index ba402cbe84..72a4aea202 100755
--- a/tests/ts/lsfd/mkfds-bpf-prog
+++ b/tests/ts/lsfd/mkfds-bpf-prog
@@ -36,7 +36,7 @@ FD=3
 	"${TS_CMD_LSFD}" -r -n -oBPF-PROG.TYPE,BPF-PROG.TYPE.RAW -p "${PID}" -Q "(FD == $FD)"
 	echo "BPF-PROG.TYPE,BPF-PROG.TYPE.RAW": $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-cdev-tun b/tests/ts/lsfd/mkfds-cdev-tun
index 25bf03efce..7354509c4d 100755
--- a/tests/ts/lsfd/mkfds-cdev-tun
+++ b/tests/ts/lsfd/mkfds-cdev-tun
@@ -57,7 +57,7 @@ IFNAME=
 	    echo "output TUN.IFACE: $output"
 	fi
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-directory b/tests/ts/lsfd/mkfds-directory
index ef769c916b..738cb86885 100755
--- a/tests/ts/lsfd/mkfds-directory
+++ b/tests/ts/lsfd/mkfds-directory
@@ -101,7 +101,7 @@ esac
 	    echo 'stat reports:' "$(stat -c %h /)"
 	fi
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-eventfd b/tests/ts/lsfd/mkfds-eventfd
index 5fa58427e8..02c86a604a 100755
--- a/tests/ts/lsfd/mkfds-eventfd
+++ b/tests/ts/lsfd/mkfds-eventfd
@@ -96,7 +96,7 @@ ENDPOINTS=
 	    echo 'lsfd:' "$tmp"
 	fi
 
-	kill -CONT ${PID0}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-eventpoll b/tests/ts/lsfd/mkfds-eventpoll
index 0d0cc68ce0..230d6c480d 100755
--- a/tests/ts/lsfd/mkfds-eventpoll
+++ b/tests/ts/lsfd/mkfds-eventpoll
@@ -38,7 +38,7 @@ FD2=7
 	echo 'ASSOC,TYPE,NAME,EVENTPOLL.TFDS': $?
 	${TS_CMD_LSFD} -J -p "${PID}" -n -o ASSOC,TYPE,NAME,EVENTPOLL.TFDS -Q "${EXPR}"
 	echo 'ASSOC,TYPE,NAME,EVENTPOLL.TFDS (JSON)': $?
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-inotify b/tests/ts/lsfd/mkfds-inotify
index 6d29c7c99f..728c27de20 100755
--- a/tests/ts/lsfd/mkfds-inotify
+++ b/tests/ts/lsfd/mkfds-inotify
@@ -65,7 +65,7 @@ EOF
 	    echo "INOTIFY.INODES.RAW": "$INODES_RAW_JSON"
 	fi
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-mapped-packet-socket b/tests/ts/lsfd/mkfds-mapped-packet-socket
index a1fb68f985..12c5ef6bc9 100755
--- a/tests/ts/lsfd/mkfds-mapped-packet-socket
+++ b/tests/ts/lsfd/mkfds-mapped-packet-socket
@@ -49,7 +49,7 @@ for SOCKTYPE in RAW DGRAM; do
 	${TS_CMD_LSFD} -p "$PID" -n -o NAME,SOCK.TYPE,SOCK.PROTONAME,PACKET.IFACE,PACKET.PROTOCOL -Q "${EXPR}"
 	echo 'NAME,SOCK.TYPE,SOCK.PROTONAME,PACKET.IFACE,PACKET.PROTOCOL': $?
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
     ERR=$?
diff --git a/tests/ts/lsfd/mkfds-mqueue b/tests/ts/lsfd/mkfds-mqueue
index 3023f1e005..fac1a793f6 100755
--- a/tests/ts/lsfd/mkfds-mqueue
+++ b/tests/ts/lsfd/mkfds-mqueue
@@ -74,7 +74,7 @@ ENDPOINTS=
 	    echo 'lsfd:' "$tmp"
 	fi
 
-	kill -CONT ${PID0}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-netlink-groups b/tests/ts/lsfd/mkfds-netlink-groups
index 896b50cef5..b7646c2284 100755
--- a/tests/ts/lsfd/mkfds-netlink-groups
+++ b/tests/ts/lsfd/mkfds-netlink-groups
@@ -47,7 +47,7 @@ NETLINK_GROUPS=5
 	else
 	    printf "LPORT: FAILED (PID: %d != NETLINK.LPORT: %d)\n" "${PID}" "${NETLINK_LPORT}"
 	fi
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-netlink-protocol b/tests/ts/lsfd/mkfds-netlink-protocol
index c1a5ffc20d..abf2eb2ca2 100755
--- a/tests/ts/lsfd/mkfds-netlink-protocol
+++ b/tests/ts/lsfd/mkfds-netlink-protocol
@@ -46,7 +46,7 @@ NETLINK_GROUPS=5
 	else
 	    printf "LPORT: FAILED (PID: %d != NETLINK.LPORT: %d)\n" "${PID}" "${NETLINK_LPORT}"
 	fi
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-netns b/tests/ts/lsfd/mkfds-netns
index cd110f6cca..3666879786 100755
--- a/tests/ts/lsfd/mkfds-netns
+++ b/tests/ts/lsfd/mkfds-netns
@@ -61,7 +61,7 @@ INO_NS=
 	    echo "NAME_FD: $NAME_FD" == "net:[INO_NS: $INO_NS]": $?
 	fi
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-pidfd b/tests/ts/lsfd/mkfds-pidfd
index aad693ff11..b5eaef94e9 100755
--- a/tests/ts/lsfd/mkfds-pidfd
+++ b/tests/ts/lsfd/mkfds-pidfd
@@ -40,7 +40,7 @@ EXPR="(PID != ${TARGET}) and (FD == 3) and (PIDFD.PID == ${TARGET})"
 	${TS_CMD_LSFD} -n -o ASSOC,STTYPE,SOURCE,NAME,PIDFD.COMM,PIDFD.PID -p "${PID}" -p ${TARGET} -Q "${EXPR}"
 	echo 'ASSOC,STTYPE,SOURCE,NAME,PIDFD.COMM,PIDFD.PID': $?
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-ping b/tests/ts/lsfd/mkfds-ping
index c2ca049ab0..21777426ae 100755
--- a/tests/ts/lsfd/mkfds-ping
+++ b/tests/ts/lsfd/mkfds-ping
@@ -122,7 +122,7 @@ for i in 0 1; do
 			   -o ASSOC,TYPE,NAME,SOCK.STATE,SOCK.TYPE,${COLNS[$i]}.LADDR,${COLNS[$i]}.RADDR,PING.ID \
 			   -p "${PID}" -Q "${EXPR[$i]}"
 	    echo "ASSOC,TYPE,NAME,SOCK.STATE,SOCK.TYPE,${COLNS[$i]}.LADDR,${COLNS[$i]}.RADDR,PING.ID": $?
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
 
@@ -132,7 +132,7 @@ for i in 0 1; do
 			   -o ASSOC,TYPE,NAME,SOCK.STATE,SOCK.TYPE,${COLNS[$i]}.LADDR,${COLNS[$i]}.RADDR,PING.ID \
 			   -p "${PID}" -Q "${EXPR[$i]}"
 	    echo "ASSOC,TYPE,NAME,SOCK.STATE,SOCK.TYPE,${COLNS[$i]}.LADDR,${COLNS[$i]}.RADDR,PING.ID": $?
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
     } > "$TS_OUTPUT" 2>&1
     wait "${MKFDS_PID}"
diff --git a/tests/ts/lsfd/mkfds-pipe-no-fork b/tests/ts/lsfd/mkfds-pipe-no-fork
index e28aa9df1d..f2f950a878 100755
--- a/tests/ts/lsfd/mkfds-pipe-no-fork
+++ b/tests/ts/lsfd/mkfds-pipe-no-fork
@@ -116,7 +116,7 @@ EOF
 	    echo EXPECTED_LSFD_ENDPOINTS_JSON: "${EXPECTED_LSFD_ENDPOINTS_JSON}"
 	fi
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-raw b/tests/ts/lsfd/mkfds-raw
index 0260ba1d9a..5770340440 100755
--- a/tests/ts/lsfd/mkfds-raw
+++ b/tests/ts/lsfd/mkfds-raw
@@ -40,7 +40,7 @@ PROTOCOL=5
 		       -o ASSOC,TYPE,NAME,SOCK.STATE,SOCK.TYPE,INET.LADDR,INET.RADDR,RAW.PROTOCOL \
 		       -p "${PID}" -Q "${EXPR}"
 	echo 'ASSOC,TYPE,NAME,SOCK.STATE,SOCK.TYPE,INET.LADDR,INET.RADDR,RAW.PROTOCOL': $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 
     wait "${MKFDS_PID}"
diff --git a/tests/ts/lsfd/mkfds-raw6 b/tests/ts/lsfd/mkfds-raw6
index 0b82fff330..1eddea28f9 100755
--- a/tests/ts/lsfd/mkfds-raw6
+++ b/tests/ts/lsfd/mkfds-raw6
@@ -41,7 +41,7 @@ PROTOCOL=5
 		       -o ASSOC,TYPE,NAME,SOCK.STATE,SOCK.TYPE,INET6.LADDR,INET6.RADDR,RAW.PROTOCOL \
 		       -p "${PID}" -Q "${EXPR}"
 	echo 'ASSOC,TYPE,NAME,SOCK.STATE,SOCK.TYPE,INET6.LADDR,INET6.RADDR,RAW.PROTOCOL': $?
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
 
     wait "${MKFDS_PID}"
diff --git a/tests/ts/lsfd/mkfds-ro-block-device b/tests/ts/lsfd/mkfds-ro-block-device
index ad5a492045..7b14630022 100755
--- a/tests/ts/lsfd/mkfds-ro-block-device
+++ b/tests/ts/lsfd/mkfds-ro-block-device
@@ -72,7 +72,7 @@ EXPR=
 
 	lsfd_compare_dev "${TS_CMD_LSFD}" "${LSFD_LOOP_BDEV}" "${EXPR}"
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-ro-regular-file b/tests/ts/lsfd/mkfds-ro-regular-file
index a2c4c268b8..367a07d560 100755
--- a/tests/ts/lsfd/mkfds-ro-regular-file
+++ b/tests/ts/lsfd/mkfds-ro-regular-file
@@ -70,7 +70,7 @@ EXPR=
 
 	lsfd_compare_dev "${TS_CMD_LSFD}" $target "${EXPR}"
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-rw-character-device b/tests/ts/lsfd/mkfds-rw-character-device
index 85dd29cad6..3df29447e9 100755
--- a/tests/ts/lsfd/mkfds-rw-character-device
+++ b/tests/ts/lsfd/mkfds-rw-character-device
@@ -42,7 +42,7 @@ EXPR=
 
 	lsfd_compare_dev "${TS_CMD_LSFD}" $target "${EXPR}"
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-signalfd b/tests/ts/lsfd/mkfds-signalfd
index 8e7d5f19b1..ecc737968a 100755
--- a/tests/ts/lsfd/mkfds-signalfd
+++ b/tests/ts/lsfd/mkfds-signalfd
@@ -56,7 +56,7 @@ EXPR='(FD == '"$FD"')'
 	${TS_CMD_LSFD} -p "${PID}" -n -o "${COL}" -Q "${EXPR}"
 	echo "${COL}": $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-socketpair b/tests/ts/lsfd/mkfds-socketpair
index 3ffd0888e8..64984d9464 100755
--- a/tests/ts/lsfd/mkfds-socketpair
+++ b/tests/ts/lsfd/mkfds-socketpair
@@ -40,7 +40,7 @@ EXPR=
 	${TS_CMD_LSFD} -n -o ASSOC,MODE,STTYPE,SOURCE,SOCK.PROTONAME -Q "${EXPR}" | sed -e 's/UNIX-DGRAM/UNIX/'
 	echo 'ASSOC,MODE,STTYPE,SOURCE,SOCK.PROTONAME': ${PIPESTATUS[0]}
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-symlink b/tests/ts/lsfd/mkfds-symlink
index 482564519f..56eccca6cd 100755
--- a/tests/ts/lsfd/mkfds-symlink
+++ b/tests/ts/lsfd/mkfds-symlink
@@ -37,7 +37,7 @@ EXPR=
 	${TS_CMD_LSFD} -n -o ASSOC,MODE,TYPE,NAME,FLAGS -Q "${EXPR}"
 	echo 'ASSOC,MODE,TYPE,NAME,FLAGS': $?
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1
diff --git a/tests/ts/lsfd/mkfds-tcp b/tests/ts/lsfd/mkfds-tcp
index e1ebbec92f..666cf6ac11 100755
--- a/tests/ts/lsfd/mkfds-tcp
+++ b/tests/ts/lsfd/mkfds-tcp
@@ -42,7 +42,7 @@ EXPR='(TYPE == "TCP") and (FD >= 3) and (FD <= 5)'
 		       -p "${PID}" -Q "${EXPR}"
 	echo 'ASSOC,TYPE,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,INET.LADDR,INET.RADDR,TCP.LADDR,TCP.LPORT,TCP.RADDR,TCP.RPORT': $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-tcp6 b/tests/ts/lsfd/mkfds-tcp6
index 609ef98877..bffa630c46 100755
--- a/tests/ts/lsfd/mkfds-tcp6
+++ b/tests/ts/lsfd/mkfds-tcp6
@@ -43,7 +43,7 @@ EXPR='(TYPE == "TCPv6") and (FD >= 3) and (FD <= 5)'
 		       -p "${PID}" -Q "${EXPR}"
 	echo 'ASSOC,TYPE,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,INET6.LADDR,INET6.RADDR,TCP.LADDR,TCP.LPORT,TCP.RADDR,TCP.RPORT': $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-timerfd b/tests/ts/lsfd/mkfds-timerfd
index 4b6e96d758..d2e0b8a535 100755
--- a/tests/ts/lsfd/mkfds-timerfd
+++ b/tests/ts/lsfd/mkfds-timerfd
@@ -50,7 +50,7 @@ ts_init_subtest "realtime-remaining-and-interval"
 	${TS_CMD_LSFD} -p "${PID}" -n -o TIMERFD.INTERVAL -Q "${EXPR}"
 	echo 'TIMERFD.INTERVAL': $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
@@ -76,7 +76,7 @@ ts_init_subtest "monotonic-remaining-only"
 	${TS_CMD_LSFD} -p "${PID}" -n -o TIMERFD.INTERVAL -Q "${EXPR}"
 	echo 'TIMERFD.INTERVAL': $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
@@ -100,7 +100,7 @@ ts_init_subtest "boottime-interval-only"
 	${TS_CMD_LSFD} -p "${PID}" -n -o TIMERFD.INTERVAL -Q "${EXPR}"
 	echo 'TIMERFD.INTERVAL': $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-timerfd-alarm b/tests/ts/lsfd/mkfds-timerfd-alarm
index ba8d27545b..bd40d559d4 100755
--- a/tests/ts/lsfd/mkfds-timerfd-alarm
+++ b/tests/ts/lsfd/mkfds-timerfd-alarm
@@ -47,7 +47,7 @@ EXPR='(FD == '"$FD"')'
 	    ${TS_CMD_LSFD} -p "${PID}" -n -o TIMERFD.INTERVAL -Q "${EXPR}"
 	    echo 'TIMERFD.INTERVAL': $?
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
     done
diff --git a/tests/ts/lsfd/mkfds-udp b/tests/ts/lsfd/mkfds-udp
index f202100405..3d1b272538 100755
--- a/tests/ts/lsfd/mkfds-udp
+++ b/tests/ts/lsfd/mkfds-udp
@@ -60,7 +60,7 @@ for lite in 0 1; do
 		       -p "${PID}" -Q "${EXPR[$lite]}"
 	echo "ASSOC,TYPE,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,INET.LADDR,INET.RADDR,${COLNS[$lite]}.LADDR,${COLNS[$lite]}.LPORT,${COLNS[$lite]}.RADDR,${COLNS[$lite]}.RPORT": $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 
@@ -85,7 +85,7 @@ for lite in 0 1; do
 	    echo "NAME pattern match: FAILED (NAME=$NAME)"
 	fi
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 
@@ -115,7 +115,7 @@ for lite in 0 1; do
 	    echo "LADDR/LPORT pattern match: FAILED (LADDR=$LADDR, LPORT=$LPORT)"
 	fi
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 
@@ -130,7 +130,7 @@ for lite in 0 1; do
 		       -p "${PID}" -Q "${EXPR[$lite]}"
 	echo 'ASSOC,TYPE,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,INET.LADDR,INET.RADDR,UDP.LADDR,UDP.LPORT,UDP.RADDR,UDP.RPORT': $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 done > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-udp6 b/tests/ts/lsfd/mkfds-udp6
index eb8d3054e5..26bdacd7c8 100755
--- a/tests/ts/lsfd/mkfds-udp6
+++ b/tests/ts/lsfd/mkfds-udp6
@@ -61,7 +61,7 @@ for lite in 0 1; do
 		       -p "${PID}" -Q "${EXPR[$lite]}"
 	echo "ASSOC,TYPE,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,INET6.LADDR,INET6.RADDR,${COLNS[$lite]}.LADDR,${COLNS[$lite]}.LPORT,${COLNS[$lite]}.RADDR,${COLNS[$lite]}.RPORT": $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 
@@ -86,7 +86,7 @@ for lite in 0 1; do
 	    echo "NAME pattern match: FAILED (NAME=$NAME)"
 	fi
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 
@@ -116,7 +116,7 @@ for lite in 0 1; do
 	    echo "LADDR/LPORT pattern match: FAILED (LADDR=$LADDR, LPORT=$LPORT)"
 	fi
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 
@@ -131,7 +131,7 @@ for lite in 0 1; do
 		       -p "${PID}" -Q "${EXPR[$lite]}"
 	echo "ASSOC,TYPE,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,INET6.LADDR,INET6.RADDR,${COLNS[$lite]}.LADDR,${COLNS[$lite]}.LPORT,${COLNS[$lite]}.RADDR,${COLNS[$lite]}.RPORT": $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 done > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-unix-dgram b/tests/ts/lsfd/mkfds-unix-dgram
index c8b40eb0d5..79e475a133 100755
--- a/tests/ts/lsfd/mkfds-unix-dgram
+++ b/tests/ts/lsfd/mkfds-unix-dgram
@@ -47,7 +47,7 @@ make_state_connected()
 		       -p "${PID}" -Q "${EXPR}" | make_state_connected
 	echo 'ASSOC,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,UNIX.PATH': ${PIPESTATUS[0]}
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 
@@ -60,7 +60,7 @@ make_state_connected()
 		       -p "${PID}" -Q "${EXPR}" | make_state_connected
 	echo 'ASSOC,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,UNIX.PATH': $?
 
-	kill -CONT "${PID}"
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait "${MKFDS_PID}"
 } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-unix-in-netns b/tests/ts/lsfd/mkfds-unix-in-netns
index cfca087b15..9ed456701c 100755
--- a/tests/ts/lsfd/mkfds-unix-in-netns
+++ b/tests/ts/lsfd/mkfds-unix-in-netns
@@ -78,7 +78,7 @@ for t in stream dgram seqpacket; do
 
 	    compare_net_namespaces "$t" "${PID}"
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
 
@@ -94,7 +94,7 @@ for t in stream dgram seqpacket; do
 
 	    compare_net_namespaces "abstract $t" "${PID}"
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
     } > "$TS_OUTPUT" 2>&1
diff --git a/tests/ts/lsfd/mkfds-unix-stream b/tests/ts/lsfd/mkfds-unix-stream
index fe08e72035..3c31443dbe 100755
--- a/tests/ts/lsfd/mkfds-unix-stream
+++ b/tests/ts/lsfd/mkfds-unix-stream
@@ -46,7 +46,7 @@ EXPR='(((TYPE == "UNIX-STREAM") or (TYPE == "UNIX")) and (FD >= 3) and (FD <= 5)
 			   -p "${PID}" -Q "${EXPR}" | lsfd_strip_type_stream
 	    echo 'ASSOC,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,UNIX.PATH': ${PIPESTATUS[0]}
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
 
@@ -59,7 +59,7 @@ EXPR='(((TYPE == "UNIX-STREAM") or (TYPE == "UNIX")) and (FD >= 3) and (FD <= 5)
 			   -p "${PID}" -Q "${EXPR}" | lsfd_strip_type_stream
 	    echo '(abs) ASSOC,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,UNIX.PATH': ${PIPESTATUS[0]}
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
 
@@ -75,7 +75,7 @@ EXPR='(((TYPE == "UNIX-STREAM") or (TYPE == "UNIX")) and (FD >= 3) and (FD <= 5)
 	    echo '(shutdown) ASSOC,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,UNIX.PATH': ${PIPESTATUS[0]}
 	    # Surprisingly, the socket status doesn't change at all.
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
 
@@ -88,7 +88,7 @@ EXPR='(((TYPE == "UNIX-STREAM") or (TYPE == "UNIX")) and (FD >= 3) and (FD <= 5)
 			   -p "${PID}" -Q "${EXPR}" | lsfd_strip_type_stream
 	    echo 'ASSOC,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,UNIX.PATH': ${PIPESTATUS[0]}
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
 
diff --git a/tests/ts/lsfd/mkfds-unix-stream-requiring-sockdiag b/tests/ts/lsfd/mkfds-unix-stream-requiring-sockdiag
index 64bdae0eb3..c188464b2c 100755
--- a/tests/ts/lsfd/mkfds-unix-stream-requiring-sockdiag
+++ b/tests/ts/lsfd/mkfds-unix-stream-requiring-sockdiag
@@ -46,7 +46,7 @@ EXPR='(((TYPE == "UNIX-STREAM") or (TYPE == "UNIX")) and (FD >= 3) and (FD <= 5)
 			   -p "${PID}" -Q "${EXPR}" | lsfd_strip_type_stream
 	    echo 'ASSOC,STTYPE,NAME,SOCK.STATE,SOCK.TYPE,SOCK.LISTENING,UNIX.PATH': ${PIPESTATUS[0]}
 
-	    kill -CONT "${PID}"
+	    echo DONE >&"${MKFDS[1]}"
 	fi
 	wait "${MKFDS_PID}"
 
diff --git a/tests/ts/lsfd/option-pid b/tests/ts/lsfd/option-pid
index 0ea4353e3e..003b624ae3 100755
--- a/tests/ts/lsfd/option-pid
+++ b/tests/ts/lsfd/option-pid
@@ -72,7 +72,7 @@ POUT=
 	[ "${QOUT}" = "${POUT}" ]
 	echo "EQ[-p PID --pid=1]:" $?
 
-	kill -CONT ${PID}
+	echo DONE >&"${MKFDS[1]}"
     fi
     wait ${MKFDS_PID}
 } > $TS_OUTPUT 2>&1